Silylated block copolymers

ABSTRACT

Alkali metal terminated organic polymers are reacted with silicon containing compounds having aliphatic unsaturation to produce a new class of reactive silylated organic polymers. These silylated organic polymers can in turn be reacted with cyclic siloxanes to produce silylated organic-organopolysiloxane block copolymers which are useful as protective coatings, surfactants and as elastomers.

This application is a division of application Ser. No. 645,733, filedDec. 31, 1975 and now U.S Pat. No. 4,080,400 which was a division ofapplication Ser. No. 533,051, filed Dec. 16, 1974, and now abandoned.

The present invention relates to organic polymers containing siliconatoms, particularly to silylated organic polymers and more particularlyto silylated organic-organopolysiloxane block copolymers.

Heretofore, copolymers have been prepared by reacting alkali metalterminated organic polymers free of silicon atoms with cyclic siloxanes.(See U.s. Pat. Nos. 3,483,270 and 3,051,684 to Bostick and Morton et al,respectively.) However, neither of these references disclose theformation of silylated polymers by reacting alkali metal terminatedorganic polymers with silicon compounds having aliphatic unsaturation ofform organic polymers containing silicon atoms. Moreover, thesereferences do not disclose silylated organic-organopolysiloxane blockcopolymers or a method for preparing the same.

Therefore, it is an object of this invention to prepare silylatedorganic polymers. Another object of this invention is to providesilylated organic-organopolysiloxane block copolymers. Still anotherobject of this invention is to provide a method for preparing silylatedorganic polymers. A further object of this invention is to provide amethod for preparing silylated organic-organopolysiloxane blockcopolymers.

These and other objects which will become apparent from the followingdescription are accomplished in accordance with this invention,generally speaking, by reacting (A) alkali metal terminated organicpolymers with (B) silanes containing aliphatic unsaturation in thepresence of an aprotic solvent to produce silylated organic polymers ofthe formula ##STR1## where M is an alkali metal, Y is the organicpolymer and the unsatisfied valences of the silicon atom are satisfiedby a hydrocarbon radical or Y. These silylated organic polymersdescribed above may be further reacted with other silanes containingaliphatic unsaturation or with unsaturated monomers capable of anionicpolymerization to form block copolymers of silylated organic polymers.These silylated organic polymers or block copolymers are reacted withcyclic siloxanes to form silylated organic-organopolysiloxane blockcopolymers.

More specifically, these polymers may be prepared by reacting acarbanion producing catalyst with unsaturated monomers in the presenceof an aprotic solvent. Examples of suitable carbanion producingcatalysts are alkali metals such as lithium, sodium, potassium,rubidium, cesium and organoalkali metal compounds such as lithiumnaphthalene, lithium anthracene, butyl lithium, vinyl lithium, lithiumstilbene, biphenyl lithium, 1,4-dilithiobenzene, 1,5-dilithiopentane,1,5-dilithionaphthalene, 1,2-dilithio-1,3,3-triphenylpropane,1,3,5-trilithiopentane, sodium naphthalene, notassium naphthalene,rubidium naphthalene, cesium naphthalene, sodium anthracene, potassiumanthracene, rubidium anthracene, cesium anthracene, sodium stilbene,potassium stilbene, rubidium stilbene, cesium stilbene, 9-fluorenylsodium, 9-fluorenyl potassium, 9-fluorenyl cesium, diphenyl sodium,diphenyl potassium, diphenyl rubidium, diphenyl cesium and the like.monalkylene

The term "aprotic solvent" refers to any organic solvent which is freeof active protons. These may include hydrocarbon solvents such asheptane, benzene, toluene and xylene and the like. It is preferred butnot necessary that an aprotic solvent capable of coordinating with thealkali metal be employed. These include nonacid oxygen containing andnitrogen containing organic solvents such as tetrahydrofuran,tetrahydropyrane, diethoxyethane; alkyl ethers such as diethyl ether,dibutyl ether, methyl ethyl ether; higher boiling ethers such asmonoalkylene glycol dialkyl ethers, dialkylene glycol monoalkyl ethers,dialkylene glycol dialkyl ethers and monoal kylene glycol monoalkylethers, dimethyl acetamide, N-methylpyrrolidine, isobutylene oxide,dimethyl sulfoxide, dioxane, diethyl ether of diethylene glycol, andvarious tertiary amines such as dimethyl aniline, tributylamine,pyridine and the like. For obvious reasons, solvents which contain anacid hydrogen should be avoided.

Any unsaturated monomer that may be polymerized by anionicpolymerization techniques may be employed in this invention. Also, anypolymerized substituted olefin having C. unsaturation is operative inthis invention. Specific examples of suitable monomers are hydrocarbonolefins such as ethylene, butadiene, styrene, vinyltoluene,divinylbenzene, isoprene, unsaturated esters such as the acrylates andalkyl substituted acrylates, e.g., methylacrylate, methylmethacrylate,ethylacrylate, butylacrylate and unsaturated nitriles such asacrylonitrile, methacrylonitrile and the like.

The reaction between the carbanion forming catalyst and the unsaturatedorganic polymers may be conducted at any temperature below 150° C.preferably below about 100° C. and more preferably between about 0° C.and 50° C.

The alkali metal terminated organic polymers thus formed may be reactedwith silicon compounds containing aliphatic unsaturation. These siliconcompounds may be represented by the general formula ##STR2## where R isa monovalent hydrocarbon radical, X is a member selected from the classconsisting of halogen, hydrocarbonoxy radicals, acyloxy radicals,phosphato radicals, sulfato radicals, perchlorate radicals, or any othergroups which are reactive with the alkalimetal carbanion, a is a numberof from 1 to 4 and b is a number of from 1 to 3.

Suitable examples of radicals represented by X are halogens such aschlorine, fluorine, bromine and iodine; acyloxy radicals of the formula##STR3## in which R' is hydrogen or an organic radical such as an alkylor aryl radical having from 1 to 18 carbon atoms; hydrocarbonoxyradicals of the formula -OR" in which R" is an organic radical such asalkyl or aryl radicals of from 1 to 10 carbon atoms; phosphato radicalsof the formula ##STR4## in which R' is the same as above; sulfurcontaining radicals of the formula SO_(y) where y is an integer of from2 to 4 and chlorates of the formula -C10₄.

Suitable examples of alkyl radicals represented by R are methyl, ethyl,propyl, butyl, pentyl, hexyl, octyl, decyl, octadecyl and the like; arylradicals such as phenyl, naphthyl, biphenyl and the like; alkarylradicals such as tolyl, xylyl, ethylphenyl and the like; aralkylradicals such as benzyl, phenylethyl and the like. The organic radicalsrepresented by R' and R" may be the same as the alkyl and aryl radicalsrepresented by R.

Examples of suitable silanes having aliphatic unsaturation which may beemployed in the preparation of the silylated organic polymers arevinyltrichlorosilane, divinyldichlorosilane, divinyldiacetoxysilane,dimethoxymethylvinylsilane, methylvinyldiacetoxysilane,dimethylvinylbromosilane, trimethylvinylsilane, tributylvinylsilane,phenylmethylvinylchlorosilane, dibutylvinylacetoxysilane and the like.

The reaction between the alkali metal terminated organic polymers andthe silanes containing aliphatic unsaturation may be carried out in thepresence or absence of a solvent. It is oreferred that the reaction beconducted in the presence of aprotic solvents which are capable ofcoordinating with the alkali-metal cation. Surprisingly, it has beenfound that when such solvents are employed, the alkali-metal carbanionpreferably reacts with the halogen or other reactive groups before itreacts with the C═C unsaturated group, thus permitting a greater degreeof control of molecular weight and chain branching. The aprotic solventsemployed may be the same as those described heretofore. Although theamount of solvent is not critical, it is preferred that from 1 to 95percent by weight of solvent be presented based on the weight of thealkali metal organic polymers and unsaturated silanes.

Generally, the reaction is carried out at a temperature of from about 0°to 150° C. And more preferably from about 10° to 50° C. Higher or lowertemperatures may however be employed, if desired.

The preparation of the alkali metal terminated organic polymers may beillustrated by the following equations, although these are not intendedto limit the scope of the invention. ##STR5##

The reaction between the resulting organometallic hydrocarbon compoundof equation (1) and the silane containing an unsaturation aliphaticgroup may be illustrated in the following manner.

When the polystyryllithium compound is reacted with, for example,vinyltrichlorosilane, a branched silicon-hydrocarbon polymer is formed.##STR6##

When the polystyryllithium compound is reacted with for example, atrimethylvinylsilane, as illustrated below a linear silicon hydrocarbonpolymer is formed. ##STR7##

In accordance with the invention thehydrocarbonsilylethyl-1-alkali-metal can be reacted with a cycliorganopolysiloxane to form block copolymers containingsilicon-hydrocarbon segments and organopolysiloxane segments. Cyclicorganopolysiloxanes which can be used in the method of this inventioninclude those of the formula (R₂ SiO)_(n) in which n is at least 3 andmay be up to 10 in which R is the same as above. the reaction ispreferably carried out in the presence of an aprotic solvent and morepreferably in the presence of an aprotic solvent which is capable ofcoordinating with the catalyst. The same aprotic solvents as describedabove may be employed in this reaction. In carrying out the reaction,the reaction temperature is not critical and may range from 25° C. toabout 200° C. and more preferably from about 25° C. to 150° C. However,higher or lower temperatures may be employed, if desired.

Suitable examples of cyclic organopolysiloxanes which may be employed inthe reaction are hexamethylcylotrisiloxane, 1,3,5,-trimethyl-1,3,5-triphenylcyclotrisiloxane, octamethylcyclotetrasiloxane,octaphenylcyclotetrasiloxane, decamethylcyclopentasiloxane,pentamethylpentaphenylcyclopentasiloxane, hexadecamethycycloctasiloxaneand the like.

The reaction between the alkali metal silylated hydrocarbon polymers andhexamethylcyclotrisiloxane (D₃) may be illustrated by the followingequations. ##STR8##

The hydrocarbon-silylethyl -1-alkali metal can be further reacted withother monomers containing other olefinic unsaturation and/or other vinylcontaining silanes to form silylated hydrocarbon polymers havingmultiple branched or linear chains of repeating units. The resultingsilylated hydrocarbon polymers described above can then be reacted withcyclic organopolysiloxanes such as described above to form silylatedhydrocarbon organopolysiloxane block copolymers in which the silylatedhydrocarbon polymers contain multiple branched or linear chains. Thefollowing equations illustrate the general reactions, but are notintended to limit the scope of this invention. ##STR9##

The silylated organic polymers and the copolymers consisting ofsilylated organic polymers and organopolysiloxanes which contain themetal carbanion or metal silanolate, respectively, may be reacted withvarious compounds to remove the reactive sites in the polymer. Examplesof suitable compounds are water; carboxylic acids such as acetic acid,oxalic acid, formic acid, maleic acid and the like; carboxylic acidanhydrides such as acetic anhydride, phthalic anhydride, maleicanhydride and the like; inorganic acids such as hydrochloric,hydroiodic, hydrofluoric, hydrobromic, sulfuric, nitric, perchloric andthe like; alcohols such as methanol, ethanol, isopropanol, 1-butanol andthe like; silanes which have at least one functional group selected fromthe class consisting of halogen, acyloxy, phosphato, sulfato,hydrocarbonoxy and perchlorato radicals such as trimethylchlorosilane,dimethyldichlorosilane, methyltrichlorosilane, silicon tetrachloride,trimethylacetoxysilane, dimethyl disulfato silane,methyltrimethoxysilane, methyltris (diethylphosphato) silane and thelike.

The silylated organic polymers and silylated organic-organopolysiloxanecopolymers may be vulcanized by the conventional techniques known in theart. For example, when polydiene units are present, vulcanization ispossible with sulfur as well as with other chemicals which have beenused for curing natural rubber. Other vulcanization agents which may beused in place of sulfur are disulfides, alkyl phenol sulfides,p-dinitrosobenzene, sulfur dichloride, tetramethyl thiuram disulfide,tetraethyl thuran disulfide, etc. Any conventional process known to theart may be employed in the vulcanization of the above polymers such asby milling and heating in the presence of vulcanizing agents.

The silylated organic polymers and silylated organic-organopolysiloxaneblock copolymers obtained from vinyl monomers can be cured using theconventional curing agents employed in heat curable organopolysiloxanecompositions. Examples of suitable curing agents are organic peroxidessuch as dicumyl peroxide, benzoyl peroxide, bis(2,4-dichlorobenzoyl)peroxide, tertiary butyl perbenzoate, high energy radiation and thelike.

Moreover, these polymers may be combined with various silane or siloxanecross-linking agents known in the art to form room temperature or heatvulcanizable compositions. Examples of suitable cross-linking agents aresilanes and siloxanes containing acyloxy groups having up to 10 carbonatoms such as methyltriacetoxysilane, tetraacetoxysilane and the like;silanes and siloxanes containing aryloxy or alkoxy groups such astetraethylorthosilicate, ethyl silicate "40"; silanes containing aminogroups such as methyltricyclohexyl aminosilane, hydrogen containingsilanes such as methylhydrogenpolysiloxanes and the like. Othercross-linking agents which may be employed are silanes or siloxanescontaining other groups which are hydrolyzable at room temperature suchas oximo groups, aminooxy groups, amides and phosphato groups. Compoundssuch as titanates, tin salts of carboxylic acids and platinum compoundsmay be employed as catalysts to accelerate the curing of thesecompositions. Also, temperatures of from 25° C. may be used toaccelerate curing.

These polymers and copolymers may be compounded with various additives,depending on the particular properties desired, before they are cured.Suitable examples of these additives are stabilizers, plasticizers,fillers preferred the like.

The block copolymers obtained herein, especially in the cured state canbe employed in the manufacture of high temperature sealants, e.g., asgaskets, rings, tubing, fuel lines, insulation, motor mountings and thelike.

The embodiments of this invention are further illustrated by thefollowing examples in which all parts are by weight unless otherwisespecified.

EXAMPLE I

Approximately 6 parts of a 1.5 molar solution of n-butyl lithium (0.01mole) in heptane and 15 parts of tetrahydrofuran are added to a roundbottom flask equipped with a stirrer. A nitrogen atmosphere ismaintained in the flask. The mixture is cooled to 0° C. and 9.6 parts oftertiary-butyl styrene are added dropwise. The reaction mixture isstirred 0.5 hour at room temperature and then the reaction mixture iscooled to 0° C. About 0.46 part of methylvinyldichlorosilane is addeddropwise to the reaction mixture. The temperature is maintained at 0° to10° C. throughout the addition. The reaction mixture is stirred 1 hourat room temperature, then 0.06 part of acetic acid is added and thelithium acetate precipitate thus formed is removed by filtration. Thesilylated hydrocarbon polymer is isolated from the solvent by vacuumstripping. Analysis of the product indicates that it has the followingstructure. ##STR10##

The molecular weight of the product is about 2900. The theoretical valuecalculated is about 3148. This illustrates that silylated hydrocarbonpolymers may be prepared having a predetermined amount of branching anda predetermined molecular weight.

EXAMPLE II

The procedure of Example I is repeated except that 9-fluorenyl sodium issubstituted in the same mole ratio for the n-butyl lithium. Essentiallythe same results are obtained.

EXAMPLE III

About 109.8 parts of a 1.5 molar solution of n-butyl lithium (1.18moles) in heptane and 75 parts of tetrahydrofuran are added to a roundbottom flask equipped with a stirrer. A nitrogen atmosphere ismaintained in the flask. The mixture is cooled to 0° C. and 76.2 partsof styrene are added over a twenty minute period. The temperaturethroughout the addition is maintained at 0° to 10° C. The reactionmixture is stirred one hour at room temperature, then 8.6 parts ofmethylvinyldichlorosilane is added over a one minute period and theresulting reaction mixture is stirred for an additional hour at roomtemperature. The resulting silylated hydrocarbon polymer may berepresented by the general formula ##STR11##

About 108.3 parts of hexamethylcyclotrisiloxane and 110 parts of benzeneare added to the reaction mixture. The mixutre is refluxed for about 4.5hours, then about 5 parts of acetic acid are added and the lithiumacetate precipitate thus formed is removed by filtration. The silylatedpolystyryl-dimethylpolysiloxane copolymer is isolated by vacuumstripping. A grease-like composition is obtained which may berepresented by the general formula ##STR12##

Nuclear Magnetic Resonance analysis confirms the ratio of siloxane topolystyrene of 1:0.48. Molecular weight analysis indicates a molecularweight of about 3390. The theoretical value calculated for this productis approximately 3262. This example demonstrates that silylatedhydrocarbon-organopolysiloxane copolymers may be prepared having apredetermined number of silylated hydrocarbon units andorganopolysiloxane units.

EXAMPLE IV

The procedure of Example III is repeated except that an equal molaramount of 9-fluorenyl potassium is substituted for the n-butyl lithium.A silylated polystyrene-dimethylpolysiloxane copolymer having a lowermolecular weight than the copolymer prepared in Example III is obtained.

EXAMPLE V

The procedure of Example III is repeated except that 7.8 parts ofdimethyldichlorosilane are substituted for themethylvinyldichlorosilane. The resulting product is a heterogeneousmaterial containing a solid and liquid phase. Analysis of the solidphase indicates a composition of the general formula ##STR13##

The liquid phase appears to be a product of the general formula##STR14##

This example further illustrates that copolymers are formed whenvinylfunctional silanes are employed.

EXAMPLE VI

The procedure of Example III is repeated except that 5.86 parts ofmethyltrivinylsilane are substituted for methylvinyldichlorosilane. Theresulting product is represented by the general formula ##STR15##

EXAMPLE VII

The procedure of Example III is repeated except that 49.6 parts ofisoprene are substituted for the styrene. A silylatedpolyisoprene-organopolysiloxane copolymer is identified.

EXAMPLE VIII

The procedure of Example IV is repeated except that 108.3 parts ofoctamethylcyclotetrasiloxane are substituted for thehexamethylcyclotrisiloxane. Substantially the same results are obtainedas in Example IV. This example shows that any cyclic organopolysiloxanemay be used in the preparation of copolymers of this invention.

EXAMPLE IX

The product obtained from Example VI (100 parts) is mixed with 5 partsof methyltriacetoxysilane in a nitrogen atmosphere and then exposed toatmospheric moisture. After about 20 hours, an insoluble rubber-likematerial is obtained.

Although specific examples of the invention have been described herein,it is not intended to limit the invention solely thereto, but to includeall the variations and modifications falling within the spirit and scopeof the appended claims.

What is claimed is:
 1. A composition obtained from the reaction of asilylated organic polymer and an unsaturated monomer capable of beingpolymerized by anionic polymerization and having carbon-to-carbonunsaturation, said silylated organic polymer is obtained from thereaction of a silane of the formula ##STR16## where R is a monovalenthydrocarbon radical, X is selected from the class consisting of halogen,acyloxy radicals, hydrocarbonoxy radicals, sulfato radicals, phosphatoradicals and perchlorato radicals, a is a number of from 1 to 4 and b isa number of from 1 to 3, with a carbanion containing organic polymer,said carbanion containing polymer is obtained from the polymerization ofan unsaturated organic monomer having a carbn-to-carbon double bond inthe presence of a carbanion forming catalyst.
 2. The composition##STR17## of claim 1, wherein the unsaturated monomer is a vinylcontaining silane.
 3. A method for preparing the composition of claim 1which comprises reacting a silylated organic polymer with an unsaturatedmonomer capable of being polymerized by anionic polymerization andhaving carbon-to-carbon unsaturation, said silylated organic polymer isobtained by reacting a silane of the formula ##STR18## where R is amonovalent hydrocarbon radical, X is selected from the class consistingof halogen, acyloxy radicals, hydrocarbonoxy radicals, sulfato radicals,phosphato radicals and perchlorato radicals, a is a number of from 1 to4 and b is a number of from 1 to 3, with a carbanion containing organicpolymer, in the presence of an aprotic solvent said carbanion containingpolymer is obtained by polymerizing an unsaturated organic monomerhaving a carbon-to-carbon double bond in the presence of a carbanionforming catalyst.
 4. The method of claim 3, wherein the unsaturatedmonomer is a vinyl containing silane.
 5. The method of claim 3, whereinthe silylated organic polymer is obtained by reactingvinyltrichlorosilane with a carbanion containing organic polymer.